Fossils from the Upper Musasbino of Kazusa and Shimosa. ^33 



Genns TRESUS, Gray. 



203. Ti-es9is »tuff alt (Conrad). 

 PI. VIII. Fig. 8. 



Tresus jiuttali. Danker, Ind. Moll., p. 184. Pilsbry, Cat., p. 120. Tokunaga, Foss. 



Env. Tokyo, p. 42. Arnold, Pal. a. Strat. San Pedro, California, p. 178. 

 Lntruria nuttali. Conrad, Jour. Acad. Nat. Sei. Pliil., vol. VII, 1837, p. 235, pi. XVIII 



fig. 1. Lischke, Jap. Meeresconcb., I, p. 136. Branns, Geol Env. Tokio, p. 38, 



pi. IV, fig. 6. 

 Lntinria maxhiui. Middendorff, Mai. Pioss., Ill, p. 66, pi. XIX, figs. 1-4. Eeeve, 



Conch, Icon., Lutraria, pi. V, fig. 18. Non L. maxima Jonas. 



This large shell excellently ligured by Brauns is frequent both 

 living and fossil in the neighbourhood of Tokyo. 



Although comparatively thin-shelled in general, some of the 

 fossil specimens are rather tliick and attain the length of 165 

 millim. with the height of 120 millim. 



Fossil occurrence in Japan. — Otake (quite frequent), Shisui, 

 Tega, Shito (frequent). Oji and Shinagawa in Musashi. 



Fossil occurrence in America. — Pliocene and Pleistocene of 

 San Pedro, California. 



Living. — Northern, Central and Western Japan. Alaska to 

 San Diego on the west coast of America. 



Genus I.SITKAKIA, Lamarck. 



sol. liUfrai'ia tmiœhtui, Jonas. 



PI. VIII, Fjgs. 9. 10. 



Lutraria maxima. Jonas, Zeitscbr. f. Malak., 1844, p. 34 (non L. maxima Midd.). 

 Keeve, Conch. Icon., Lutraria, pi. Ill, fig. 11. Lischke;, Jap. Meeresconcb., I, p. 

 138. Pilsbry, Cat., p. 120. 



Ciiaracterized by a transversely elongate-oblong, compressed, 

 very inequilateral shell more than twice as long as high. The 

 surface is smooth. 



This shell is somewhat like Lutrcu^la ovalis Tokunaga (Foss. 

 Env. Tokyo, p. 41, pi. II, fig. 28) from Shinagawa Avhich is 

 possibly identical with Lutraria sleboldi Reeve (no. 15 of his Conch. 

 Icon.), but it is decidedly longer. 



